The overall objective of the proposed program is the synthesis of di- and tripeptides composed of amino acids azaserine and 6-diazo-5- oxonorleucine (DON). Biological evaluation of these peptides is expected to answer a number of questions and provide a better insight into the antitumor activity of these compounds. During the second year we expect to complete the synthesis of the following: cyclic dipeptides of DON and 5-diazo-4-oxonorvaline, open dipeptides of azaserine and DON. In addition, dipeptides in which either azaserine or DON is combined with a different amino acid either at the N-terminal or the C-terminal will be prepared. Based on this experience, the synthesis of selected tripeptides such as azotomycin will be undertaken. This last phase may require further extension of the grant period which we hope to obtain.